Digital clock

ABSTRACT

A digital clock wherein four numerals corresponding to minutes, tens of minutes, hours and tens of hours are simultaneously displayed. Three rotatable cams are provided for successively indexing the minutes, tens of minutes and hours display indicators, and the cam for the hours display indicator also actuates the tens of hours display indicator. A unique indexing mechanism is positioned between the minutes cam and the tens of minutes cam for indexing the minutes cam one increment each minute and for simultaneously indexing the tens cam one increment at the instant of the tenth actuating increment of the minutes cam.

ljited States Patent [191 oyles et al.

[54] lDllGlTAL CLOCK [75] inventors: Robert L. Boyles, Wayland; Samuel Polonsky, Medway, both of Mass.

[73] Assignee: General Electric Company, Bridgeport, Conn.

22 Filed: Nov. 8, 1971 21 Appl.N0.:196,479

[52] US. Cl. ..58/126 E, 58/2, 58/23 R, 58/50 R, 58/125 R [51] Int. Cl. ..G04b 19/00, G041) 19/02 [58] Field of Search ..58/l25 C, 2, 126 E, 125 R, 58/50 R, 85.5, 34, 126 R [451March 20, 1973 2,645,896 7/1953 Uhlig et al. ..58/l25 C 2,762,190 9/1956 Holzner ..58/85.5 X 2,734,338 2/1956 Uhlig et al. .58/125 C 2,985,998 5/1961 Holzner ..58/126 E Primary Examiner-Richard B. Wilkinson Assistant ExaminerStanley A. Wal Attorney-Lawrence R. Kempton et al.

[57] ABSTRACT [56] References Cited tens of hours display indicator. A unique indexing UNITED STATES PATENTS mechanism is positioned between the minutes cam and the tens of minutes cam for indexing the minutes 2,968,143 1/1961 Meyer ..58/l25 cam one increment each minute and for simultane- 3,260,343 6 McCormick ously indexing the tens cam one increment at the in- 2 3 V1967 Emem et stant of the tenth actuating increment of the minutes 3,397,585 8/1968 McGowan cam 3,465,605 9/1969 Hylan 2,587,277 2/1952 Bergman ..58/85.5 10 Chims, 12 Drawing Figures 2,596,370 5/1952 Bush ..53/l25 C X in illllllllll Z4 I 1 nmuum l I// l L /40 mmnnmnn O I. I l l l l. I I111 l 1 l 1- l 1:

PATENTEADHAREO 1m 3,721. 087' PATENTEUMARZO I975 SHEET 30F 5 Ass, hag

m5 Z n 6 WWW DIGITAL CLOCK BACKGROUND OF THE INVENTION This invention relates to a digital clock, and more particularly to a unique indexing and drive arrangement for the numeral display indicators of {a digital clock which indicate minutes, tens of minutes, hours and tens of hours.

In a co-pending application of Robert L. Boyles Ser. No. 105,854, filed Jan. 12, 1971, now US. Pat. No. 3,683,523 and assigned to the same assignee as the present invention, there is disclosed a display indicator having a plurality of horizontal and vertical bars or lines arranged in the shape of a numeral 8 for indicating numerals from thru 9. As shown in the application, the numerals from 0 thru 9 may be readily formed from seven straight line indicator bars which are arranged in the shape of the FIG. 8. The seven indicator bar segments include three generally parallel horizontally arranged bars and two pairs of generally vertically arranged bars positioned on opposite sides of the horizontal bars. With this arrangement, should it be desired to display a numeral 1, all bar segments except the two right vertical segments would be blocked out. To form the numeral 0, it is only necessary to block out the middle horizontal bar. It follows that the numeral 3 may be formed by blocking out the two left vertical bars. This invention is concerned with arranging four display indicators in close proximity with respect to each other for displaying minutes, tens of minutes, hours and tens of hours. Our invention is particularly concerned with a unique drive arrangement for appropriately indexing the units, tens, hours and tens of hours display indicators so that the numerals which are displayed by these indicators are quickly indexed from one numeral to the next succeeding numeral.

Accordingly, it is a primary object of this invention to provide an improved indexing and drive arrangement for time display indicators which may be manufactured at relatively low cost for quickly and simultaneously indexing a units, tens of units, hours and tens of hours display indicator.

SUMMARY OF THE INVENTION In accordance with one of the aspects of this invention, a digital clock includes a plurality of display indicators for visually displaying a set of numerals from 0 thru 9 to indicate the time of day. A rotatable units cam is positioned adjacent to a minutes display indicator for progressively actuating the units display indicator to display numerals from 0 thru 9 to indicate minutes. A rotatable tens cam is spaced to the left of the units cam for progressively actuating the tens of minutes display indicator for displaying numerals to the left of the minutes in order to display tens of minutes. A unique indexing mechanism is mounted between the minutes cam and the tens cam for indexing the units cam one incentral portion to the drive lever. The pawl lever has a pawl formed on one of its side portions for engaging the units cam for moving the units cam one increment each minute, and the pawl lever also has a pawl formed on its other side portion for engaging and moving the tens cam an increment every ten minutes. By this arrangement, both the units cam for indexing the units display indicator and the tens cam for indexing the tens display indicator are actuated by the same pawl indexing mechanism which is conveniently positioned and pivoted between the units and tens cams. Moreover, the pawl lever may be counterweighted with more weight in the vicinity of the pawl which engages the units cam to normally hold the pawl above the tens cam. Thus, the pawl lever exerts relatively weak forces on the digital clock mechanism and may be moved and actuated by a low power motor.

BRIEF DESCRIPTION OF THE DRAWING Other objects and attendant advantages of the invention will be apparent from the following description taken in connection with the accompanying drawing in which:

FIG. 1 is a front elevational view of a digital clock constructed in accordance with our invention;

FIG. 2 is a fragmentary front elevational view of a portion of the mechanism for setting and indexing the minutes, tens of minutes, hours and tens of hours display indicators of the digital clock shown in FIG. 1;

FIG. 3 is a fragmentary front elevational view of a portion of the cam mechanism for actuating the minutes, tens of minutes, hours and tens of hours display indicators of the digital clock shown in FIG. 1;

FIG. 4 is a fragmentary exploded front perspective view of the drive cam mechanism for successively indexing the minutes, tens of minutes and hours display indicators of the digital clock shown in FIG. 1;

FIG. 5 is a fragmentary front elevational view showing portions of the vertically movable shutters of the units, tens and hours indicators along with the cam mechanisms for driving them of the digital clock shown in FIG. 1;

FIG. 6 is a fragmentary front elevational view of portions of the horizontally movable shutters and the drive cams for the shutters of the digital clock shown in FIG.

FIG. 7 is a fragmentary side elevational view of a portionof the drive mechanism the digital clock shown in FIG. 1;

FIG. 8 is a fragmentary exploded perspective view of the indexing mechanism for the units, tens and hours cams for the display indicators of the clock shown in FIG. 1;

FIG. 9 is a front elevational diagrammatic view of the units and tens cam indexing mechanism of the digital clock shown in FIG. 1, the parts being shown in the position wherein the minutes cam is being indexed one increment;

FIG. 10 is a front elevational diagrammatic view similar to FIG. 9 with the parts being shown in the position wherein both the minutes cam and the tens cam are being indexed one increment;

FIG. 11 is a front elevational diagrammatic view similar to FIG. 9 with the parts being shown in the position wherein the drive lever for the units and tens cam is being returned to a starting position after the drive lever has indexed the units cam one increment; and

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing and first particulariy to FIGS. 1, 2 and 3, there is shown a digital clock which includes our unique indexing and drive arrangement for appropriately actuating four numeral display indicators 2, 4, 6 and 8 which indicate minutes, tens of minutes, hours, and tens of hours, respectively.

The digital display indicators 2, 4 and 6 for displaying minutes, tens of minutes, and hours may be substantially identical to each other, and inthe preferred embodiment of the invention illustrated in FIGS. 1, 4, and 6, it can be appreciated that each display indicator includes a plurality of horizontal and vertical bars or lines arranged in the shape of a numeral 8 for indicating numerals from 0 thru 9. There are seven indicator bar segments including three generally parallel horizontally arranged bars 10, 12 and 14, and two pairs of generally vertically arranged bars 16, 18, and 22 positioned on opposite sides of the horizontal bars. Thus, should it be desired to display a numeral 1 all bar segments except the two right vertical segments would be blocked out.

In the embodiment illustrated in FIG. 1, it can be seen that the right three display indicators 2, 4 and 6 are displaying numerals 5,3 and 2, respectively. Thus, in display indicator 2 the lower right and upper left vertical bars are blocked out. In display indicator 4 the two left vertical bars are blocked out, and in display indicator 6 the upper right and lower left vertical segments are blocked out. The details of the right three display indicators 2, 4 and 6 do not form a part of this invention and are described and illustrated in greater detail in a co-pending application of Robert L. Boyles, Ser. No. 105,854, assigned to the same assignee as the present invention.

As shown in FIG. 1, the display indicators 2, 4 and 6 include a common front plate 24 which may be formed of a sheet of plastic that may be readily slotted or blocked out to reveal three clear numeral 8s, one for each of the display indicators 2, 4 and 6. With particular reference to FIGS. 4 and 5, each of the display indicators 2, 4 and 6 includes a vertically movable shutter 30, 32 and 34, respectively, for selectively blocking out one or more of the horizontal indicator bars 10, 12 and 14. It can be appreciated that all of the horizontal bars should be blocked out for displaying a numeral 1 while only the central bar 12 should be blocked out for displaying the numeral 0. To achieve this, a plurality of opaque shutter bars 36, 38 and 40 may be painted or otherwise formed on the vertically movable shutter members 30, 32 and 34 for blocking out the appropriate horizontal indicator bars. The shutters may be formed of a relatively thin plastic material, and with such a construction, light which emanates from lamps 42 and 44 or other suitable light source may flow through the clear portions of the shutters 30, 32 and 34, and hence, through any of the unobstructed generally horizontal bars 10, 12 and 14 of the slotted numeral 8.

With particular reference to FIGS. 4 and 6, horizontally slidable shutters 46 and 48 and 50 are positioned behind the vertically slidable shutters for selectively obstructing the vertical bars 12, 16, 18 and 22 of the slotted FIG. 8 numerals of the display indicators 2, 4 and 6. It can be appreciated that the upper left vertical bar 18 should be blocked out to display numerals l, 2 and 3 while it would be unobstructed to display the numerals 6, 8 and 9, for example.

It can be readily appreciated that in order to display a particular numeral the vertical shutter has to be moved to one position while the horizontally movable shutter is required to be moved to a different position. For example, in order to display the numeral 2 as shown in FIG. 1, the vertically movable shutter has to be moved to leave all of the horizontal bars 10, 12 and 14 unobstructed. In a similar manner the horizontally movable shutter has to be moved to block out only the lower right and upper left vertical indicator bars 20 and 18, respectively.

As shown more particularly in FIGS. 4, 5 and 7, twofaced rotatable cams 52, 54 and 56 are provided for moving the vertical shutters 30, 32 and 34, respectively, and the horizontal shutters 46, 48 and 50, respectively. The front faces of each of the cams include a cam groove 60 for receiving a cam follower 62 in order to appropriately position the vertically movable shutters 30, 32 and 34. The cam followers 62 may be integrally formed on a lever 64 which is connected at one end to the vertically movable shutters 30, 32 and 34 by means of a pivot 66 formed on the lever and a slot 68 integrally formed in the lower portion of the vertical shutters 30, 32 and 34. The other ends of the levers for the vertically movable shutters may be suitably pivotally connected at 63 to the front plate 24 of the display indicators.

With particular reference to FIGS. 4, 6 and 7, a cam groove 70 is formed in the rear face of the rotatable cams 52, 54 and 56 for moving the horizontal shutters 46, 48 and 50 back and forth behind the vertical shutters 30, 32 and 34. As shown, a cam follower 72 which isformed on a lever 74 is positioned within the cam track 70 on the rear surface of the cams 52, 54 and 56. The levers 74 may be mounted on the digital clock by means of pivots which may conveniently extend through the apertures 76. A slot 78 is formed in the upper arms of the levers for receiving rearwardly extending lugs 80 which may be integrally formed on the horizontal shutters 46, 48 and 50. With this construction, when the cams 52, 54 and 56 are rotated in a clockwise direction as illustrated in FIGS. 4, 5 and 6, the front cam groove and cam follower causes the vertical sliders to move upwardly and downwardly with respect to the slotted numeral 8 members, and the rear cam track 70 causes the cam follower 72 and the lever 74 to move the horizontal shutters 46, 48 and 50 to the right and left behind the vertical shutters and the slotted numeral 8.

The horizontal and vertical shutters 46 and 30, respectively, and the cam groove arrangement for moving them are illustrated and described in greater detail in the aforementioned co-pending application of Robert L. Boyles, assigned to the same assignee as the present invention.

MINUTES AND TENS OF MINUTES CAM INDEXING AND DRIVE ARRANGEMENT A unique mechanism is positioned between the units and tens cams 52 and 54 for indexing the minutes cam once every minute and for simultaneously indexing the tens cam one increment at the instant that the units cam is being indexed a 10 increment, so that the units cam and the tens cam are simultaneously indexed to the next succeeding numbers when the units cam is being moved to its 10 increment. To achieve this, special cam teeth 80 and 82 are integrally formed on the outer periphery of the earns 52 and 54 for cooperating with a pawl lever 84 which is positioned between the cams. As shown more particularly in FIGS. 8, 9, l and 11, the unique indexing mechanism includes a drive lever 86 which is pivotally mounted on the digital clock between the units and tens cams 52 and 54, respectively. In order to suitably support the drive lever 86 on the clock, the lever 86 may include an integrally formed pivot shaft 88 having reduced end portions 90 and 92 which may be suitably sandwiched within apertures 94 and 96 which are formed in plates 98 and 100 of the digital clock.

An arrangement for oscillating the drive lever 86 to provide a rapid clockwise advance stroke of about seconds duration and a slower return stroke once per minute is shown more particularly in FIGS. 8, 9, and 11. To accomplish this, the drive lever 86 is provided with two cam surfaces 102 and 104 for cooperating with an eccentric drive roller 106 mounted on a gear 108 that is rotated at one revolution per minute by a synchronous electric motor pinion 110. While the motor for driving the pinion 110 is not illustrated, it can be appreciated that it is a particular advantage that our unique drive arrangement may be operated with a synchronous motor having a relatively low power output.

With particular reference to FIG. 9, it can be seen that the gear 108 and its eccentric roller 106 are rotated in a clockwise direction and when the roller 106 reaches the position illustrated in FIG. 9, it abuts the surface of the rapid advance cam 102 to pivot the upper portion of the drive lever 86 to the right about its lower pivot-88 to move a units pawl 112 of the pawl lever 84 to the right, as shown in FIG. 9, against a tooth 1140f the units cam to move the units cam 52 one increment to thereby actuate the units display indicator 2 to display a next succeeding numeral. With particular reference to FIG. 11, it can be appreciated that continued rotation of the eccentric roller moves the roller into contact with the return stroke cam surface 104 to move the drive lever 86 and the pawl lever 84 to the left as shown in FIG. 11.

In accordance with our invention the pawl lever 84 is uniquely shaped, weighted and pivoted so that the relatively small pawl lever 84 may reliably index both the units cam 52 and the tens cam 54. The pawl lever 84 includes a central portion 116 which is loosely pivoted to the drive lever 86 by a pivot pin 118, a right-side portion having a units pawl 112 formed thereon for indexing the units cam and a left-side portion having a pawl 120 formed thereon for indexing the tens cam 54. As shown more particularly in FIG. 8, the pawl 84 is uniquely weighted by a counterweighted portion 113 in the vicinity of the units pawl 112 so that the pawl 112 gently rests on the units cam 52 as shown in FIG. 8. In this position, it can be appreciated that the tens pawl is located above the teeth 82 on the tens cam 54. Thus, during nine of the 10 incremental movements of the pawl lever 84, the tens pawl 120 clears the teeth 82 on the tens cam 54, and consequently, the tens cam 54 remains stationary.

During the tenth incremental movement of the drive lever 86 our unique mechanism indexes both the units cam 52 and the tens cam 54 simultaneously so that the succeeding numerals will simultaneously appear at the display indicators 2 and 4. To accomplish this the 10 tooth 122 on the units cam is made much higher than the other nine teeth 114 of the units cam which correspond to numerals 1 thru 9. With particular reference to FIG. 10 it can be seen that as the eccentric roller 106 pushes on the advance cam surface 102, the weighted pawl lever 112 slides upwardly on the high tooth 122 to pivot the pawl lever 84 counterclockwise about pivot 118 from the position illustrated in FIG. 9 to the position illustrated in FIG. 10. This causes the left tens pawl 120 to be moved downwardly to engage one of the teeth 82 on the tens cam. Accordingly, the units pawl 112 is in engagement with the high tooth 122 on the units cam, and tens pawl 120 is in engagement with one of the teeth on the tens cam 54, and further rotation of the eccentric roller 106 against the rapid advance cam 102 will cause the drive lever 86 and the pawl lever 84 to be moved to the right as shown in FIG. 10 to index both the units cam 52 and the tens cam 54 one increment. It can be appreciated that this movement of both cams occurs simultaneously, and thus, a person viewing our improved digital clock will observe a simultaneous change in both the units and the tens numerals which appear on display indicators 2 and 4, respectively.

HOURS INDEXING MECHANISM With the mechanism thus far described, it can be appreciated that the units display indicator 2 is rapidly indexed one incremental movement each minute by the eccentric roller 106 when it is moved against the rapid advance cam 102 and that the units and tens display indicators 2 and 4 are simultaneously rapidly indexed to their next succeeding positions once every 10 minutes when the parts are in the positions illustrated in FIG. 10. In accordance with our invention, a unique mechanism is also provided for rapidly indexing the hours digital display indicator 6 once every hour. The mechanism for achieving this is driven from the tens cam 54, and thus, the mechanism is arranged to simultaneously index the hours display indicator 6 on every sixth indexing movement of the tens cam. As shown more particularly in FIGS. 1, 2, 3, 4 and 8, a six slotted geneva gear 124 and a two lug geneva driver 126 are positioned between the tens cam 54 and an hours cam 56. As shown more particularly in FIG. 4, the geneva driver 126 is positioned on the same axis as the tens cam gear 54 and may be directly keyed thereto by means of a radial lug 128 which is integrally formed with the tens cam gear 54. In like manner, an hour gear 130 may be positioned on the same axis as the hour cam 56 and keyed to the hour cam by means of a lug 132. The geneva gear 124 may be formed of plastic to include an integrally formed toothed gear 134 which is arranged in mesh with the hour gear 130.

With particular reference to FIGS. 1, 2 and 3, it can be appreciated that the geneva gear 124 and its integrally formed toothed gear 134 are positioned between the geneva driver 126 and the hour gear 130. It can be seen that the tens of minutes cam 54 is provided with 12 teeth and the geneva driver 126 is formed to include two lugs 136 and 138 for driving the geneva gear 124. Thus, with this unique low cost arrangement on every sixth incremental movement of the tens of minutes cam 54 one of the drive lugs 136 or 138 is brought into engagement with one of the six notches of the geneva gear to move the geneva gear one incremental movement to thereby advance the hour digital display indicator 6 to the next succeeding number.

TENS OF HOURS INDEXING MECHANISM In accordance with our invention, a unique low cost arrangement is provided for indicating tens of hours. In a conventional 12 hour clock mechanism it can be appreciated that the only numeral that has to be displayed for indicating the tens of hours is the numeral 1. This numeral represents the first numeral of the three succeeding hours 10, 11 and 12. Thus, to display any of the time positions from 1 oclock to 9 oclock the tens of hours numeral could be a 0 or it would not be necessary to display any numeral. In the embodiment of our digital clock illustrated in FIG. 1, it is desired to display a numeral 1 or no number to indicate the tens of hours. As shown more particularly in FIGS. 1 and 5, in order to achieve this the tens of hours digital display indicator 8 is not provided with a slotted numeral 8, but merely includes a generally vertical slot 140 for displaying a numeral 1 and a single shutter 142 is positioned behind the slotted numeral 1 for selectively blocking it out during the time positions from 1 oclock to 9 oclock while leaving the slot open to display a numeral 1 for the 10 oclock, I 1 oclock and 12 oclock positions. The mechanism for indexing the shutter 142 from the 9 oclock to the 10 oclock position and from the 12 oclock to the 1 oclock position is achieved with the use of relatively few additional parts. To accomplish this the hours cam gear 56 is uniquely formed with an additional cam surface 144 on its outer periphery for operating the tens of hours shutter 142. As shown more particularly in FIG. 3, the tens of hours shutter 142 is formed with a rightwardly extending lug 146 which is urged by gravity against the peripheral cam surface 144 of cam 56. With the arrangement illustrated it can be appreciated that on the 10 incremental movement of the geneva gear 124 and the hours cam 56, the lug 146 is moved from a high cam surface 150 of cam 144 to a low cam surface 152 of cam 144 to thereby permit shutter 142 to move from behind slot 140 in order to display a numeral 1. Thus, the numeral 1 forms the first or tens numeral as the digital clock is moved to its 10 oclock position. The lower surface 152 of cam 144 is three increments in length, and thus, the lug 146 remains on the lower surface 152 of the cam 144 during the l0, l1 and 12 oclock positions of our digital clock. It can be appreciated that as the geneva gear 124 rapidly makes its 13 incremental movement the lug 146 will be rapidly moved from the low cam surface 152 to the high cam surface 150 in order to block out the numeral 1 of the tens of hours indicator. At this time it can be appreciated that no numeral would be displayed in the tens of hours position while the numeral 1 would be displayed on the hours indicator 6 to show the 1 oclock position of the digital clock.

TIME SET ARRANGEMENT A low cost mechanism is uniquely incorporated with the aforedescribed structure for setting or resetting the digital display indicators 2, 4, 6 and 8 of our improved digital clock to indicate the correct time of day. As shown more particularly in FIGS. 2, 4 and 12, our setting mechanism is achieved by the provision of relatively few additional parts. The principal component of the setting mechanism is a push-pull knob 154 which may rotate and slide on a stud 156 which is formed on a front wall of the clock. As illustrated, a four-tooth sprocket or pinion 158 is integrally formed with the knob 154 for selective engagement with a lO-tooth sprocket 160 which is connected to the units cam 52 and display indicator 2, or a 12-tooth sprocket 162 which is connected to the tens of minutes cam 54 and display indicator 4.

With particular reference to FIG. 4, it can be appreciated that the minutes sprocket 160 may be readily connected to the minutes cam gear 52 by a key lug 164 which is formed on a shaft portion of the minutes cam. The sprocket 162 includes 12 teeth which are integrally formed with the geneva driver 126, and the geneva driver 126 is connected to the tens of minutes cam 54 by a key lug 128 which is formed on the tens of minutes cam. As shown in FIG. 12, the time set knob 154 is normally held by two compression springs 161 and 163 in an intermediate axial position where it engages neither the units nor the tens sprocket.

In operation when it is required or desired to set our unique digital clock it is merely necessary to pull and rotate the set knob 154 in a counterclockwise direction to cause clockwise movement of the minutes pinion 160 and the minutes time display indicator 2 for setting the minutes display to its appropriate position. Then, in order to set the tens of minutes display indicator 4, the hours display indicator 6, and the tens of hours display indicator 9 to their appropriate positions, it is merely necessary to push inwardly on the set knob 154 to remove the sprocket 158 from gear 160 and place it in engagement with sprocket 162 of the tens of minutes wheel 126. In this position, rotation of the set knob 154 in a counterclockwise direction will cause clockwise rotation of the gear 162, the tens of minutes cam 54, and the geneva driver 126 which is integrally formed with the sprocket wheel 162 to set the tens of minutes display indicator 4 to its appropriate position. It can be appreciated that the hours and the tens of hours indexing mechanisms 56 and 144 are both rotatably connected to the tens of minutes indexing mechanism, and thus, rotation of the tens of minutes sprocket 162 in a clockwise direction will cause intermittent rotation of the geneva gear 124 and the combined hours and tens of hours gear 56-144.

From the foregoing discussion it will be appreciated that our improved digital clock driving mechanism and time set mechanism may be readily formed with relatively few parts. Many of the parts are arranged and shaped to perform a plurality of functions and they may be readily formed of plastic. For example, the uniquely formed hours cam 56-144 functions as both a hours cam and a tens of hours cam. A cam groove is formed in its front face for moving a vertical shutter 38, a cam groove is formed in its rear surface for moving a horizontally movable shutter 46, and a cam surface 144 is formed in its outer periphery for actuating the tens of hours shutter 142. The geneva driver 126 is also uniquely formed to perform a plurality of functions. As shown more particularly in FIG. 3, a sprocket 162 is formed on the geneva driver 126 for cooperating with the time set knob 154 in order to set our improved digital clock.

With our improved indexing mechanism it can also be appreciated that all of the display indicators are quickly moved from one number to the next succeeding number and they are moved simultaneously. The rapid advance cam 102 rapidly moves both the minutes cam gear 52 and the tens cam gear 54 at the same instant. During such movement at the appropriate times the geneva gear 124 actuates the hours and tens of hours cam gear 56-144.

Moreover, it can be seen that our reliable mechanism for indexing the minutes and tens of minutes cams 52 and 54 is achieved with relatively few low cost parts. A small pawl lever 84 is uniquely pivoted between the minutes cam and the tens of minutes cam for reliably actuating the cams. The counterweighted pawl 112 is all that is required for holding the minutes pawl into engagement with the minutes cam 52.

What we claim is:

1. A digital clock comprising:

a. two display indicators for visually displaying numerals from thru 9 to indicate minutes and tens of minutes;

b. a rotatable units cam for progressively actuating the minutes display indicator to display numerals from 0 thru 9 to indicate minutes; I

c. a rotatable tens cam spaced from the units cam for progressively actuating the tens of minutes display indicator for displaying numerals to the left of the units numerals in order to display tens of minutes;

d. a supporting means for rotatably supporting said units and tens cams on axes generally parallel to each other and spaced from each other;

e. a drive lever pivotally mounted on said supporting means between said units and tens cams; a pawl lever having a central portion and two side portions, the central portion of said pawl lever being pivotally mounted on said drive lever, said pawl lever having a pawl formed in one of its side portions for engaging the units cam for moving the units cam one increment each minute;

. said pawl lever having a pawl formed in its other side portion for engaging and moving the tens cam an increment every 10 minutes;

. means for normally holding the pawl lever into en gagement with the units cam and spaced from the tens cam;

i. means for moving said drive lever through, one complete cycle of movement each minutefor causing a corresponding single incremental movement of the units cam pawl and the units cam every minute; and i j. means on the units cam for tilting the pawl lever to engage the pawl on the other side of the pawl lever with the tens cam to permit the drive lever and the pawl lever to move the tens cam one increment every ten minutes.

2. A digital clock as defined in claim 1 wherein said pawl lever is counterweighted with more weight in the vicinity of the pawl which engages the units cam for constantly urging the pawl lever into contact with the units cam.

3. A digital clock as defined in claim 1 wherein the units cam has 10 teeth corresponding to the numerals from 0 thru 9 for cooperating with the pawl to permit the units cam to be driven through 10 increments, the teeth corresponding to numerals 1 thru 9 being relatively low in height so that when the pawl lever is in engagement with any one of said relatively low teeth the counterweighted pawl lever pivots the tens pawl above the tens cam to thereby prevent the pawl lever from actuating the tens cam whenever the units pawl is in engagement with a tooth corresponding to numerals 1 thru 9, the tooth on the units cam corresponding to numeral 0 being substantially higher than the teeth corresponding to numerals 1 thru 9 to pivot the pawl lever against the force of the counterweight to move the tens pawl into engagement with the tens cam whenever the pawl lever is in engagement with the high tooth of the units cam so that when the pawl lever is in engagement with said high tooth of the units cam with the tens pawl in engagement with the tens cam actuation of the drive lever causes actuation of the pawl lever to simultaneously move the units cam and the tens cam one increment.

4. A digital clock comprising:

a, two display indicators for visually displaying two numerals from 0 thru 9 to indicate minutes and tens of minutes;

b. a rotatable units member for progressively actuating the minutes display indicator to display numerals from 0 thru 9 to indicate minutes;

. a rotatable tens member spaced from the units member for progressively actuating the tens of minutes display indicator for displaying numerals to the left of the units numerals in order to display tens of minutes;

d. a units time set sprocket connected to said rotatable units member for rotation therewith;

. a tens time set sprocket connected to said tens member for rotation therewith; and

f. an axially movable and rotatable time set gear positioned between said units time set sprocket and said tens time set sprocket, said time set gear being axially movable inwardly to engage the tens time set sprocket in order to set the tens of minutes display indicator to the appropriate time of day, and said time set gear being axially movable outwardly to engage said units time set sprocket to rotate and set the units display indicator to the appropriate time of day.

. A digital clock comprising:

a. three display indicators for visually displaying three numerals from 0 thru 9 to indicate minutes, tens of minutes and hours;

b. a rotatable units member for progressively actuating the minutes display indicator to display numerals from 0 thru 9 to indicate minutes;

0. a rotatable tens member spaced from the rotatable units member for progressively actuating the tens of minutes display indicator for displaying numerals to the left of the units numerals in order to display tens of minutes;

d. a rotatable hours member spaced from the units and tens rotatable members for progressively actuating the hours display indicator for displaying numerals to the left of the units and tens of units numerals in order to display hours;

e. a geneva driver connected to said tens of minutes member; and

f. a geneva gear positioned between said geneva driver and said hour member for imparting an intermittent rapid motion to said hours member to move the hours member one increment for every six incremental movements of the tens member to thereby move the hours member one increment each hour.

6. A digital clock as defined in claim wherein an axially movable and rotatable time set gear and a tens time set member are operatively connected to each other for selectively rotating the geneva driver for setting the tens of minutes and hours display indicators.

7. A digital clock as defined in claim 6 wherein the tens time set member includes a plurality of teeth integrally formed with said geneva driver.

8. A digital clock comprising:

a. three display indicators for visually displaying three numerals from 0 thru 9 to indicate minutes, tens of minutes and hours;

b. a display indicator for visually displaying a numeral l to indicate tens of hours;

c. a rotatable units member for progressively actuating the minutes display indicator to display numerals from 0 thru 9 to indicate minutes;

. a rotatable tens member spaced from the rotatable units member for progressively actuating the tens of minutes display indicator for displaying numerals to the left of the units numerals in order to display tens of minutes;

e. a rotatable hours member spaced from the units and tens rotatable members for progressively actuating the hours display indicator for displaying numerals to the left of the units and tens of units numerals in order to display hours; and

f. said rotatable hours member including a cam surface for actuating said tens of hours display indicator to display a numeral 1 during the 10, 1 f and 12 oclock positions of the digital clock.

9. A digital clock as defined in claim 8 wherein said rotatable hours member is in the general form of a circular disc having a front face surface, a rear face surface, and a circumferential peripheral surface, a cam track formed in the front surface of said disc for actuating one portion of the hours display indicator, a cam track formed in the rear surface of said disc for actuating another portion of said hours display indicator and a cam surface formed on the circumferential peripheral surface of said hours member for actuating the tens of hours numeral display indicator.

10. A digital clock as defined in claim 8 wherein an axially movable and rotatable time set gear and a tens time set member are operatively connected to each other for setting the tens of minutes, hours, and tens of hours indicators. 

1. A digital clock comprising: a. two display indicators for visually displaying numerals from 0 thru 9 to indicate minutes and tens of minutes; b. a rotatable units cam for progressively actuating the minutes display indicator to display numerals from 0 thru 9 to indicate minutes; c. a rotatable tens cam spaced from the units cam for progressively actuating the tens of minutes display indicator for displaying numerals to the left of the units numerals in order to display tens of minutes; d. a supporting means for rotatably supporting said units and tens cams on axes generally parallel to each other and spaced from each other; e. a drive lever pivotally mounted on said supporting means between said units and tens cams; f. a pawl lever having a central portion and two side portions, the central portion of said pawl lever being pivotally mounted on said drive lever, said pawl lever having a pawl formed in one of its side portions for engaging the units cam for moving the units cam one increment each minute; g. said pawl lever having a pawl formed in its other side portion for engaging and moving the tens cam an increment every 10 minutes; h. means for normally holding the pawl lever into engagement with the units cam and spaced from the tens cam; i. means for moving said drive lever through one complete cycle of movement each minute for causing a corresponding single incremental movement of the units cam pawl and the units cam every minute; and j. means on the units cam for tilting the pawl lever to engage the pawl on the other side of the pawl lever with the tens cam to permit the drive lever and the pawl lever to move the tens cam one increment every ten minutes.
 2. A digital clock as defined in claim 1 wherein said pawl lever is counterweighted with more weight in the vicinity of the pawl which engages the units cam for constantly urging the pawl lever into contact with the units cam.
 3. A digital clock as defined in claim 1 wherein the units cam has 10 teeth corresponding to the numerals from 0 thru 9 for cooperating with the pawl to permIt the units cam to be driven through 10 increments, the teeth corresponding to numerals 1 thru 9 being relatively low in height so that when the pawl lever is in engagement with any one of said relatively low teeth the counterweighted pawl lever pivots the tens pawl above the tens cam to thereby prevent the pawl lever from actuating the tens cam whenever the units pawl is in engagement with a tooth corresponding to numerals 1 thru 9, the tooth on the units cam corresponding to numeral 0 being substantially higher than the teeth corresponding to numerals 1 thru 9 to pivot the pawl lever against the force of the counterweight to move the tens pawl into engagement with the tens cam whenever the pawl lever is in engagement with the high tooth of the units cam so that when the pawl lever is in engagement with said high tooth of the units cam with the tens pawl in engagement with the tens cam actuation of the drive lever causes actuation of the pawl lever to simultaneously move the units cam and the tens cam one increment.
 4. A digital clock comprising: a. two display indicators for visually displaying two numerals from 0 thru 9 to indicate minutes and tens of minutes; b. a rotatable units member for progressively actuating the minutes display indicator to display numerals from 0 thru 9 to indicate minutes; c. a rotatable tens member spaced from the units member for progressively actuating the tens of minutes display indicator for displaying numerals to the left of the units numerals in order to display tens of minutes; d. a units time set sprocket connected to said rotatable units member for rotation therewith; e. a tens time set sprocket connected to said tens member for rotation therewith; and f. an axially movable and rotatable time set gear positioned between said units time set sprocket and said tens time set sprocket, said time set gear being axially movable inwardly to engage the tens time set sprocket in order to set the tens of minutes display indicator to the appropriate time of day, and said time set gear being axially movable outwardly to engage said units time set sprocket to rotate and set the units display indicator to the appropriate time of day.
 5. A digital clock comprising: a. three display indicators for visually displaying three numerals from 0 thru 9 to indicate minutes, tens of minutes and hours; b. a rotatable units member for progressively actuating the minutes display indicator to display numerals from 0 thru 9 to indicate minutes; c. a rotatable tens member spaced from the rotatable units member for progressively actuating the tens of minutes display indicator for displaying numerals to the left of the units numerals in order to display tens of minutes; d. a rotatable hours member spaced from the units and tens rotatable members for progressively actuating the hours display indicator for displaying numerals to the left of the units and tens of units numerals in order to display hours; e. a geneva driver connected to said tens of minutes member; and f. a geneva gear positioned between said geneva driver and said hour member for imparting an intermittent rapid motion to said hours member to move the hours member one increment for every six incremental movements of the tens member to thereby move the hours member one increment each hour.
 6. A digital clock as defined in claim 5 wherein an axially movable and rotatable time set gear and a tens time set member are operatively connected to each other for selectively rotating the geneva driver for setting the tens of minutes and hours display indicators.
 7. A digital clock as defined in claim 6 wherein the tens time set member includes a plurality of teeth integrally formed with said geneva driver.
 8. A digital clock comprising: a. three display indicators for visually displaying three numerals from 0 thru 9 to indicate minuTes, tens of minutes and hours; b. a display indicator for visually displaying a numeral 1 to indicate tens of hours; c. a rotatable units member for progressively actuating the minutes display indicator to display numerals from 0 thru 9 to indicate minutes; d. a rotatable tens member spaced from the rotatable units member for progressively actuating the tens of minutes display indicator for displaying numerals to the left of the units numerals in order to display tens of minutes; e. a rotatable hours member spaced from the units and tens rotatable members for progressively actuating the hours display indicator for displaying numerals to the left of the units and tens of units numerals in order to display hours; and f. said rotatable hours member including a cam surface for actuating said tens of hours display indicator to display a numeral 1 during the 10, 11 and 12 o''clock positions of the digital clock.
 9. A digital clock as defined in claim 8 wherein said rotatable hours member is in the general form of a circular disc having a front face surface, a rear face surface, and a circumferential peripheral surface, a cam track formed in the front surface of said disc for actuating one portion of the hours display indicator, a cam track formed in the rear surface of said disc for actuating another portion of said hours display indicator and a cam surface formed on the circumferential peripheral surface of said hours member for actuating the tens of hours numeral display indicator.
 10. A digital clock as defined in claim 8 wherein an axially movable and rotatable time set gear and a tens time set member are operatively connected to each other for setting the tens of minutes, hours, and tens of hours indicators. 